CAPE Chemistry Unit 2 · 2005 · Paper 2

46 questions and parts from this paper. Open one to see it in full, then practise it on Quelpr and get it marked against the mark scheme.

1. 1(a)(i)a2 marksSuggest how the blood responds in the presence of lactic acid produced as a result of mild exercise.
2. 1(a)(i)b2 marksSuggest how the blood responds in the presence of lactic acid produced as a result of strenuous exercise.
3. 1(a)(ii)2 marksSuggest how the blood responds in the presence of excess alkalinity.
4. 1(b)4 marksOutline the steps needed to prepare a buffer solution of known pH and to determine that the solution is of the required pH.
5. 2(a)6 marksOutline a plan by which a chemist, without access to flame test rods, could use physical properties to identify the four Group II metal sulphates (Mg, Ca, Sr, Ba).
6. 2(b)(i)1 markDescribe the environmental conditions under which a photographer would have decided to use the reaction of heating magnesium in air.
7. 2(b)(ii)1 markSuggest ONE disadvantage of using the reaction of magnesium burning in air for photography.
8. 2(b)(iii)2 marksWrite the chemical equation to illustrate the reaction of magnesium burning in air.
9. 3(a)(i)1 markState what chemical feature all of the mentioned starting materials (potatoes, grapes, corn) possess.
10. 3(a)(ii)2 marksGive TWO differences in home-made alcoholic beverages resulting from the use of different starting materials.
11. 3(a)(iii)2 marksBriefly describe a simple laboratory method to determine the relative percentage alcohol in TWO home-made beverages.
12. 3(b)(i)1 markExplain why ethanol is classified as a drug.
13. 3(b)(ii)4 marksBriefly describe FOUR consequences of alcohol abuse on the social and economic structures of our society.
14. 4(a)5 marksBy reference to the Bronsted-Lowry theory and the molecular structure of niacin, explain the statement, "Niacin is a weak acid".
15. 4(b)(i)3 marksCalculate the concentration of H+ ions in the 0.020 mol dm-3 solution of niacin at 298 K.
16. 4(b)(ii)3 marksCalculate the concentrations of niacin and the conjugate base in solution at 298 K.
17. 4(b)(iii)3 marksCalculate Ka for niacin at 298 K.
18. 4(c)(i)3 marksWhat changes in the values of pH and Ka for niacin would be expected if the determination is carried out at 320 K? Suggest a reason based on molecular structure.
19. 4(c)(ii)3 marksComment on the suitability of using a weak base to determine the concentration of niacin in solution by titration.
20. 5(a)(i)1 markExplain the "muscle twitch" observed by Galvani when frog leg muscles were touched simultaneously by two different metals.
21. 5(a)(ii)3 marksDescribe with the aid of a diagram the experiment that Volta might have performed using TWO named metals to produce electricity.
22. 5(a)(iii)5 marksDescribe how the apparatus in (a)(ii) can be modified to determine the standard electrode potential.
23. 5(b)(i)2 marksStain removers oxidize coloured compounds to colourless complexes. Suggest ONE reason why an ozone-producing formulation is believed to produce brighter, whiter clothes than bleach does.
24. 5(b)(ii)2 marksComment on the suggestion that chlorine can be produced by bubbling ozone through sea water.
25. 5(c)(i)2 marksUse the data booklet to write equations for the reactions occurring at each electrode during discharge of the lead-storage battery.
26. 5(c)(ii)2 marksCalculate the standard cell potential for the lead-storage battery.
27. 5(d)3 marksBy reference to standard electrode potentials in the data booklet, deduce the useful by-product of the H2-O2 fuel cell reaction, including relevant equations.
28. 6(a)9 marksExplain how the temperature determines the products of the reaction between chlorine and aqueous sodium hydroxide, using equations to illustrate your answer.
29. 6(b)8 marksUse the given redox potential values to explain the similarities and differences in the behaviour of the halogens with the thiosulphate (S2O3 2-) ion.
30. 6(c)3 marksDescribe how silver nitrate solution can be used to distinguish among the halide ions Cl-, Br- and I-.
31. 7(a)(i)4 marksExplain why anhydrous copper (II) sulphate is a white solid that gradually turns blue upon dropwise addition of water, and dissolves to form a blue solution upon further addition.
32. 7(a)(ii)3 marksExplain why the gradual addition of concentrated sodium chloride solution to aqueous copper (II) sulphate produces a green solution, which changes to yellow upon further addition.
33. 7(b)(i)4 marksDetermine the formula of the complex ion X.
34. 7(b)(ii)1 markDraw the shape of the complex ion X.
35. 7(c)(i)4 marksExplain why the oxygen-carrying capacity of haemoglobin is reduced in the presence of carbon monoxide.
36. 7(c)(ii)4 marksAccount for why manganate(VII) ions (MnO4-) and dichromate(VI) ions (Cr2O7 2-) are powerful oxidizing agents, using E0 values where appropriate.
37. 8(a)(i)8 marksDescribe the Contact Process for the manufacture of sulphuric acid, including the raw material sources and the chemistry of the process.
38. 8(a)(ii)2 marksExplain how sulphur dioxide (SO2) modifies the atmosphere.
39. 8(b)(i)4 marksWrite an equation for the reaction between CaCO3 and SO2, and explain the underlying principle of the action of the carbonate scrubber.
40. 8(b)(ii)6 marksCalculate the mass of CaCO3, in kg, needed in a slurry to extract the SO2 present in 10 m3 of industrial waste gases at r.t.p., if SO2 comprises 10% of this volume.
41. 9(a)(i)5 marksExplain the need for concern regarding ozone depletion and human health.
42. 9(a)(ii)3 marksDescribe THREE properties of CFCs that contributed to their widespread use.
43. 9(b)(i)2 marksSuggest TWO properties of ammonia that led to its replacement by CCl2F2.
44. 9(b)(ii)5 marksUse CFC-12 as an example to write chemical equations that demonstrate the impact of CFCs on the ozone layer.
45. 9(c)(i)3 marksExplain the underlying chemical principle in this natural steady-state process of ozone formation and destruction.
46. 9(c)(ii)2 marksWrite chemical equations representing the natural processes of formation and destruction of ozone.